Fluidized drying apparatus

ABSTRACT

A fluidized drying apparatus having a substantially cylindrical casing, a perforated plate provided in said casing which divides the interior of said casing into an upper solid fluidizing chamber and a lower windbox chamber and which has formed therein a number of perforations each being inclined with respect to the axis of said casing so as to direct a drying gas passing therethrough in a direction at an acute angle to the surface of said perforated plate and means for feeding a granular material to be dried into said fluidizing chamber. A breaking member is provided in the casing above the perforated plate, which is rotated during operation of the apparatus to break lumps of material agglomerating on said perforated plate.

O Umted States Patent 91 [111 3,711,962

Fukuyo 1 Jan. 23, 1973 F LUIDIZED DRYING APPARATUS FOREIGN PATENTS ORAPPLICATIONS Inventor: asa y u ka- 1,010,460 6/1957 Germany ..34 57 1)Japan Primary Examiner-William F. ODea [73] Asslgnee' gz i i g n 2:22:?Assistant Examiner-William C. Anderson s 3 r mQgU Attorney-Ernest A.Greenside [22] Filed: Dec. 15, 1970 [57] ABSTRACT [21] Appl.No.: 98,397A fluidized drying apparatus having a substantially cylindrical casing,a perforated plate provided in said casing which divides the interior ofsaid casing into an [52] :J.S.Cll. upper solid fluidizing chamber and alower windbox g ggl chamber and which has formed therein a number of259/DIG. 17, 108, 8

perforations each being inclined with respect to the axis of said casingso as to direct a drying gas passing therethrough in a direction at anacute angle to the surface of said perforated plate and means forfeeding a granular material to be dried into said fluidizing chamber. Abreaking member is provided in the casing above the perforated plate,which is rotated during operation of the apparatus to break lumps ofmaterial agglomerating on said perforated plate.

2 Claims, 2 Drawing Figures [Q 111 u n PATENTED JAN 2 3 I975 NEEFLUIDIZED DRYING APPARATUS The present invention relates to a fluidizeddrying apparatus and more specifically to such a fluidized dryingapparatus which is provided therein with a member for breaking lumps ofgranular or powdered feed material cohering on a perforated plate in afluidizing chamber.

A conventional fluidized drying apparatus of the type wherein a granularmaterial to be dried is fed into a fluidizing chamber and dried by adrying gas swirling within said chamber, had the drawback that, wherethe feed material is cohesive, the material agglomerates on a perforatedplate in a fluidizing chamber and the socalled channeling phenomenonoccurs in which a drying gas passes only through gas passageways formedat portions of the fluidized bed of material, with the result thatuniform drying of the material cannot be attained.

The object of the present invention is to provide a fluidized dryingapparatus in which a member capable of breaking lumps of feed materialcohering onto a perforated plate in a fluidizing chamber (hereinafterreferred to as a breaking member) is provided, whereby the lumps arebroken into grains or smaller parts and kept fluidized and, therefore,the feed material is dried in an efficient manner.

According to the present invention there is provided a fluidized dryingapparatus of the type having a generally cylindrical casing, aperforated plate provided in said casing which divides said easing intoan upper solid fluidizing chamber and a lower windbox chamber, each ofthe perforations in said plate being inclined to the axis of said casingso as to direct a gas passing therethrough in operation in a directionat an acute angle to the surface of the plate, and means for feeding apowdered or granular material to be dried into said upper chamber, whichapparatus comprises a breaking member for breaking the powdered orgranular material cohering on said perforated plate.

The present invention will be described in detail hereinafter withreference to the accompanying drawings, in which:

FIG. 1 is a vertical cross-sectional front view showing diagrammaticallyan embodiment of the fluidized drying apparatus according to the presentinvention, with a breaking member provided therein; and

FIG. 2 is a vertical cross-sectional front view showing diagrammaticallyanother embodiment of the fluidized drying apparatus of the invention,with another form of the breaking member provided therein.

Referring first to FIG. 1 there is shown the first embodiment of thefluidized drying apparatus according to the present invention. Theapparatus includes a generally cylindrical casing l and a'perforatedplate 2 made of a material free of thermal deformation provided in saidcasing l, by which the interior of said casing 1 is divided into anupper solid fluidizing chamber a and a lower windbox chamber b. Each ofthe perforations 3 form ed in the perforated plate 2 is inclined at anangle to the axis of the cylindrical casing 1 so as to direct a dryinggas passing therethrough in operation in a direction at an acute angleto the surface of said plate 2.

The casing l is provided with a gas inlet port 5 for supplying a dryinggas into the windbox chamber b therethrough. Above the perforated plate2 is provided a breaking member 6 which comprises two upper and lowerrod-shaped arms extending diametrically of the casing (l) and connectedwith each other at several locations by connecting rods into the shapeof a window frame and a boss 13 provided at the center thereof. Thebreaking member 6 is connected to a drive shaft 7 through the boss 13thereof, which drive shaft is driven by a driving mechanism 8. Referencenumeral 10 designates a material outlet port for discharging the driedmaterial from the fluidizing chamber a therethrough, and 11 designates amanhole communicating with the fluidizing chamber a, through which saidfluidizing chamber is cleaned and inspected.

For drying a granular material, which is relatively hard to cohere or isrelatively high in fluidity, in the fluidized drying apparatus shown inH6. 1, a drying gas is supplied into the windbox chamber b through thegas inlet port 5 and ejected into the fluidizing chamber a through theperforated plate 3 in directions at an angle to the surface of saidperforated plate, whereby said drying gas ascends in the fluidizingchamber a while swirling about the axis thereof throughout thecylindrical space thereof. Therefore, when a granular material to bedried is thrown into the swirling gas flow from the upper side as at 3,it flows within the fluidizing chamber a about the axis thereof whilebeing entrained in the ascending swirling gas flow and is uniformlystirred, whereby the material is dried uniformly in a short period oftime, even when the grain size of the material largely varies. Uponcompletion of the drying, the dried material is automatically dischargedthrough the material outlet port 10 into a container (not shown)exterior of the apparatus, under the force of the swirling gas, whensaid material outlet port is opened. However, where the material iscohesive, only the ascending swirling flow of the drying gas formed inthe fluidizing chamber a is not sufficient to prevent the material fromagglomerating on the perforated plate 2 and the so-called channelingphenomenon occurs in which the drying gas passes only throughpassageways formed at portions of the material bed and does not passthrough the other portions of said material bed. In such a case,therefore, the breaking member 6 is driven by, the driving mechanism 8while the ascending swirling flow of the drying gas is being formedwithin the fluidizing chamber a by the perforated plate 2, whereby thematerial agglomerating on said perforated plate 2 is constantly brokeninto grains or smaller parts and kept fluidized by said breaking member6 and is dried efficiently by the drying gas passing therethrough. Thus,even a cohesive material can be broken up and kept fluidized and drieduniformly.

The second embodiment of the fluidized drying apparatus of the inventionis shown in FIG. 2. This embodiment is identical with the firstembodiment shown in FIG. 1, except for the breaking member, and the sameparts are indicated by same numerals. in FIG. 2, the breaking member 6consists of a first member 6a and a second member 6b, both of which areprovided above the perforated plate 2. The first member 6a has the shapeofa rake and extends diametrically across the casing l, with theopposite ends thereof fixed to said casing. The second member 6b alsohas the shape of a rake and extends diametrically across the casing 1,with the central portion thereof secured to a drive shaft 7 through aboss 13, which drive shaft 7 is connected to a driving mechanism 8 to bedriven thereby. The first member 6a and the second member 6b arearranged in parallel relation to each other, with the projecting prongsof the former located in the interspaces of the projecting prongs of thelatter.

In the operation of the fluidized drying apparatus of FIG. 2, when themember 6b is rotated, the agglomerating material is not only broken upby the rotating member 6b but also more forcibly broken into smallerparts or grains by a shearing force produced by the coaction of themembers 6a and 6b, so that even a more cohesive feed material whichcould not possibly be handled by the breaking member shown in FIG. 1 canbe broken up, kept fluidized, and the material is dried uniformly in ashort period of time by uniform contact with the drying gas.

What is claimed is l. A fluidized drying apparatus of the type having agenerally cylindrical casing, a single annular integral plate providedin said casing and extending transversely across the entire extent ofthe casing for dividing said casing into an upper solid fluidizingchamber adapted to receive finely divided material to be dried and alower windbox chamber into which a drying gas is adapted to beintroduced, said integral plate being formed with a plurality of closelyspaced perforations extending radially from the center of said plate tothe outer periphery thereof, with each perforation providing unimpededcommunication between the upper fluidizing chamber and the lower windboxchamber and being inclined to the axis of the casing at an angle todirect said gas passing therethrough, during operation, in a directionat an acute angle to the surface of the plate, and a rotatable breakermember extending diametrically substantially across the entire extent ofthe annular plate, said breaker member comprising first and secondspaced apart members disposed above said single perforated plate with atleast one of said members mounted for rotation about the longitudinalaxis of said casing, and drive means adapted to drive said one of saidbreaker members from a side of of said perforated annular plate oppositethe side on which said first and second breaker members are located, andoutlet means communicating with the upper chamber for discharging driedmaterial.

2. Apparatus according to claim 1, wherein said one of said members hasthe shape of a rake and extends substantially diametrically across thecasing with a central portion thereof driven by a drive shaft in turnconnected to said drive means, the other of said breaker members alsohaving the shape of a rake and extending substantially diametricallyacross said casing with the opposite ends thereof fixed to the casing,said first and second members being arranged in parallel relation toeach other with the projecting prongs of the former projecting into theinterspaces of projecting prongs of the latter.

1. A fluidized drying apparatus of the type having a generallycylindrical casing, a single annular integral plate provided in saidcasing and extending transversely across the entire extent of the casingfor dividing said casing into an upper solid fluidizing chamber adaptedto receive finely divided material to be dried and a lower windboxchamber into which a drying gas is adapted to be introduced, saidintegral plate being formed with a plurality of closely spacedperforations extending radially from the center of said plate to theouter periphery thereof, with each perforation providing unimpededcommunication between the upper fluidizing chamber and the lower windboxchamber and being inclined to the axis of the casing at an angle todirect said gas passing therethrough, during operation, in a directionat an acute angle to the surface of the plate, and a rotatable breakermember extending diametrically substantially across the entire extent ofthe annular plate, said breaker member comprising first and secondspaced apart members disposed above said single perforated plate with atleast one of said members mounted for rotation about the longitudinalaxis of said casing, and drive means adapted to drive said one of saidbreaker members from a side of of said perforated annular plate oppositethe side on which said first and second breaker members are located, andoutlet means communicating with the upper chamber for discharging driedmaterial.
 2. Apparatus according to claim 1, wherein said one of saidmembers has the shape of a rake and extends substantially diametricallyacross the casing with a central portion thereof driven by a drive shaftin turn connected to said drive means, the other of said breaker membersalso having the shape of a rake and extending substantiallydiametrically across said casing with the opposite ends thereof fixed tothe casing, said first and second members being arranged in parallelrelation to each other with the projecting prongs of the formerprojecting into the interspaces of projecting prongs of the latter.